If you're looking to use them in public, I would highly advise against the Q701 and probably HD598 (though it can be done). And unless noise cancellation is of utmost importance, you'd be overspending about $150 on the Bose.

The AKG are out because they are not sealed and will allow noise from outside sources in.

The B&W P5 is a great sounding headphone that actually seals pretty well. I use it at night when I fall asleep because it fits very comfortably and is a low profile design.

The Bose Q15 is actually a decent sounding headphone, but really should be used for noisy environments like airplanes or trams. I used a set at PAX West and actually felt that they sounded really good for being able to suppress the ambient noise so well. At the price of the Q15 you can definitely get a better sounding headphone if noise cancellation is not a concern.

The Sennheiser HD 598 is a decent enough headphone, but to they again are not sealed. They are also a little flimsy and can crack quite easily. To me the 558 and 598 sound identical. Take a look at the frequency response curve comparison.

If you go with a HD 5X8 headphones you might as well go with the less expensive 558 because it is going to sound identical to the 598.

I have not heard the Momentum and cannot comment on its sound signature. From both the reviews and the charts they look quite good. Keep in mind they are $350 and the direct comparison between them and the 558 / 598 is not going to be the same. I have no qualms in recommended this headphone based on the reviews and charts alone. They look pretty sexy to boot.

I really enjoy my DT880s. They're a balanced headphone thats a little on the bright side. They have deep bass, but not much bass slam. Mind, I don't have much experience with other headphones as I tried a couple pair of Sennheisers, which sounded ok, but they hit my jaw wrong. These sounded good and were super comfy. If you want slamming bass, look into the DT990. I haven't heard them, but almost went for it instead. Its got more bass impact, but more treble as well, and they're already pretty bright.